Zeolite beta has long been recognized as an aromatics alkylation catalyst. For instance, U.S. Pat. No. 4,891,458 discloses a process for alkylation of benzene with a C2 to C4 olefin using zeolite beta as a catalyst. The zeolite beta is the crystalline aluminosilicate originally described in U.S. Pat. No. 3,308,069. It is noted by the '458 patent that the zeolite beta should be predominantly in its hydrogen ion form in order to provide for high catalytic activity. The zeolite beta is converted to the hydrogen form by ammonium exchange followed by calcination. It is further preferred for the catalyst to be a shaped mixture of zeolite powder and an inorganic oxide binder.
U.S. Pat. No. 5,600,050 discloses the use of a modified zeolite beta as a catalyst that is used in the liquid phase alkylation of benzene to make cumene. The catalyst comprises from 30 to 70 wt. % H-beta zeolite with a silicon-to-aluminum ratio of from 20 to 40, from 0.5 to 10 wt. % of a halogen, and the balance being γ-Al2O3. The catalyst is prepared by converting a Na-beta zeolite to the H-form by ammonium exchange followed by calcination and then adding a halogen-containing compound to a mixture of the H-form beta zeolite and γ-Al2O3 precursor that is formed and calcined. It is claimed that the catalyst shows higher space-time yield and selectivity of cumene than prior art catalysts.
U.S. Pat. No. 5,672,799 teaches a process for the preparation of cumene by the alkylation of benzene with propylene using beta zeolite into which quantities of either alkaline, alkaline-earth or metallic cations have been introduced by means of ion exchange. It is asserted that the catalyst system has good activity and selectivity to cumene of the converted benzene which is higher than provided by zeolite beta that is either partially or totally in the acid form. The zeolite beta is prepared as described in U.S. Pat. No. 3,308,069 followed by its conversion to the acid form by ammonium treatment and calcination and then ion exchanged with an ion selected from Na+, K+, Ca2+ or Ni2+. The zeolite may be mixed with a binder in relative quantities of between 50:50 and 95:5.
Disclosed in U.S. Pat. No. 6,440,886 is a modified zeolite beta catalyst that is active in the alkylation of aromatics with olefin and exhibits a lower deactivation rate for a given temperature than conventional zeolite beta. The catalyst comprises a calcined, non-template surface-modified zeolite beta. To make the catalyst, an as-synthesized and templated zeolite beta is acid washed with a strong acid followed by removal of the template by calcination.
An organotemplate-free synthesis process for making zeolite beta is described in U.S. Pat. No. 8,865,121. The zeolitic materials having a BEA framework structure made by the organotemplate-free synthesis process are considered to be novel having unique properties. The process yields a zeolite with a BEA framework structure that is enriched with respect to a particular polymorph compared to the products of a BEA framework structure made by synthesis methods that use an organotemplate. The X-ray powder diffraction pattern of the beta zeolitic material of the organotemplate-free synthesis process exhibit reflections that are shifted in their 2° Theta values compared to the X-ray powder diffraction pattern of beta zeolitic material made by an organotemplate-mediated synthesis process.
U.S. Publication 20120259148 discloses an alkylation process that uses a catalyst comprising a zeolite beta obtained from a synthesis process that does not use an organotemplate as the structure directing agent. The alkylation process is broadly described as reacting an alkylatable organic compound with an alkylating agent to obtain an alkylated organic compound. However, only the two alkylation reactions of benzene with ethene and toluene with ethene are presented in the examples.
There is an ongoing desire to develop improved processes for the alkylation of benzene with propylene to make cumene. It is desirable for such processes to provide for high cumene selectivity even with reduced or low alkylation reactor inlet temperatures, high weight hourly space velocities, and reduced feed benzene-to-propylene molar ratios. Due to the unique properties of zeolite beta made by an organotemplate-free synthesis process and other of its beneficial features, it is a further object of the invention to use such a zeolite beta product as a catalyst in the production of cumene.